This cheat works even if you have an established driving profile. Simply opt to edit your profile and enter the following codes as the profile name to activate the cheat's effects. Note there is a space between the first name input and the last name input:

Unlock Everything: Gimme Gimme
Fan Level Upgrade: Super Star
Prestige Upgrade: MeMyself AndI
Max Team Prestige: All ForOne
Accrue $10 Million: Walmart Money
Walmart Bonus: Walmart Exclusive
Dale Earnhardt Sr.: The Intimidator